Morphology change of metastable regrown graphite with boron additive under HPHT

By temperature gradient method under high pressure and high temperature (HPHT), with NiMnCo alloy as the solvent metal, at diamond-stable region of about 5.4 GPa and 1500 K, metastable regrown graphite crystals of different morphology were synthesized. With B as an additive incorporated into the NiMnCo-C system, metastable regrown graphite crystals of sphere-like shape were firstly obtained under HPHT. If the growth system does not contain B, sheet-like regrown graphite crystals, most with regular hexagonal morphology, are grown upwards and standing vertically in the metal solvent. When B additive of 1.0 wt pct was added into carbon source (graphite powder), all metastable regrown graphite crystals took on the habit of regular sphere-like morphology, and were grown by a spiral layer growth mechanism. Printed by